1. Field of the Invention
The present invention relates to a reduction mechanism for driving a mill for pulverizing coal, cement or the like, and a mill having the same reduction mechanism.
2. Description of the Prior Art
In conventional reduction mechanism for driving a vertical mill for pulverizing coal, cement or the like, an impulsive pulverizing force is applied to an output table and received by a cylindrical case through a thrust bearing. However, thrust supporting portion of the thrust bearing is not so designed as to align with the center between inside and outside diameters of the cylindrical case. Even if they are aligned with each other, load is sustained by the whole surface of the thrust supporting portion of the thrust bearing.
Examples of this kind of technology are "Reduction mechanism for vertical pulverizer" described in "Industrial Machinery" (1983. 12) and the one disclosed in Japanese Patent Unexamined Publication No. 3-282045.
In the case where the thrust supporting portion of the thrust bearing is not positioned between the inside and outside diameters of a vertical portion of the cylindrical case which receives the thrust force, or in the case where the load is sustained by the whole surface of the thrust supporting portion of the thrust bearing, the cylindrical case is applied with moment load and deformed, and therefore an internal gear formed directly on the inner surface of the case is influenced by the deformation of the cylindrical case to deteriorate tooth bearing, and vibration is transmitted to the cylindrical case and the whole reduction mechanism to increase noise. However, these problems have been neglected. Further, no consideration has been given to another problem that, since the connections between the output table and a carrier and between a sun gear shaft and an intermediate shaft are made by means of rigid bodies, the sun gear can not move freely, and accordingly the tooth bearing is deteriorated and power is not distributed equally to thereby increase noise.
An object of the present invention is to provide a reduction mechanism for mill which is little suffered from deformation of a case, deterioration of tooth bearing, unequal distribution of power, and vibration and noise, and a mill having the same reduction mechanism.